Evaluation of a cone-beam computed tomography system calibrated for accurate radiotherapy dose calculation

[Display omitted] •A novel cone-beam computed tomography system was evaluated for dose calculation.•Accurate calibration of the cone-beam computed tomography was possible.•Dose calculation was within 1% of the prescribed dose for complex treatments.•This allows for direct offline and on-line re-plan...

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Bibliographic Details
Published in:Physics and imaging in radiation oncology Vol. 29; p. 100566
Main Authors: Bogowicz, Marta, Lustermans, Didier, Taasti, Vicki Trier, Hazelaar, Colien, Verhaegen, Frank, Fonseca, Gabriel Paiva, van Elmpt, Wouter
Format: Journal Article
Language:English
Published: Netherlands Elsevier B.V 01.01.2024
Elsevier
Subjects:
Cone-beam computed tomography
CT number accuracy
Dose calculation
Image quality
Metal artifact reduction
Original
Radiotherapy
Image quality
Radiotherapy
Cone-beam computed tomography
Dose calculation
CT number accuracy
Metal artifact reduction
ISSN:2405-6316, 2405-6316
Online Access:Get full text
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Summary:[Display omitted] •A novel cone-beam computed tomography system was evaluated for dose calculation.•Accurate calibration of the cone-beam computed tomography was possible.•Dose calculation was within 1% of the prescribed dose for complex treatments.•This allows for direct offline and on-line re-planning using cone-beam imaging. Dose calculation on cone-beam computed tomography (CBCT) images has been less accurate than on computed tomography (CT) images due to lower image quality and discrepancies in CT numbers for CBCT. As increasing interest arises in offline and online re-planning, dose calculation accuracy was evaluated for a novel CBCT imager integrated into a ring gantry treatment machine. The new CBCT system allowed fast image acquisition (5.9 s) by using new hardware, including a large-size flat panel detector, and incorporated image-processing algorithms with iterative reconstruction techniques, leading to accurate CT numbers allowing dose calculation. In this study, CBCT- and CT-based dose calculations were compared based on three anthropomorphic phantoms, after CBCT-to-mass-density calibration was performed. Six plans were created on the CT scans covering various target locations and complexities, followed by CBCT to CT registrations, copying of contours, and re-calculation of the plans on the CBCT scans. Dose-volume histogram metrics for target volumes and organs-at-risk (OARs) were evaluated, and global gamma analyses were performed. Target coverage differences were consistently below 1.2 %, demonstrating the agreement between CT and re-calculated CBCT dose distributions. Differences in Dmean for OARs were below 0.5 Gy for all plans, except for three OARs, which were below 0.8 Gy (<1.1 %). All plans had a 3 %/1mm gamma pass rate > 97 %. This study demonstrated comparable results between dose calculations performed on CBCT and CT acquisitions. The new CBCT system with enhanced image quality and CT number accuracy opens possibilities for off-line and on-line re-planning.
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Both authors have contributed equally.
ISSN:2405-6316
2405-6316
DOI:10.1016/j.phro.2024.100566